kth_logo.gif

Article

Unsteady jet surface visualization and primary unsteady characteristics and the effect of nozzle configuration

Authors: Gong, , Yang, , Kang, , Wang, Y.W.
Document Type: Article
Pubstate: Submitted
Journal: Flow Measurement and Instrumentation
Volume:   
Year: 2016

Abstract

Under the three breakup regimes, jet interface features associated with two kinds of nozzles are captured using high-speed microscopic photography. The transition characteristics of jet interface are measured with a spectral method. The results show that the positions where the jet interface translates from stability to instability get exponentially close to the nozzle exit with the increase of Weber number determined by air density. At the same Weber number, the transition positions fluctuate within a certain streamwise range with the variation of time and spanwise position. The transition range is in proportion to the wavelength and curvature of periodic “wave-like” structures of the instability region. These structures expand in both streamwise and spanwise directions as they move downstream. The periodicity is weaken by the coalescent and division of these primary instability structures. When the Weber number is below 40, the nozzle exit configuration has a significant effect on the wavelength and curvature, therefore, the transition of jet interface is affected. However the effect is not appreciable when the Weber number increases to 80.